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Mean spacing between Hemoglobin molecules

  1. Oct 23, 2010 #1
    1. The problem statement, all variables and given/known data
    Calculate the mean spacing between hemoglobin molecules inside a red blood cell?


    2. Relevant equations
    Diameter of red blood cell = 5 microns
    3*10^8 hemoglobin molecules in each red blood cell
    Volume of hemoglobin molecule = 8.71*10^-26 m


    3. The attempt at a solution
    I assume we take the blood cell to be a spherical model, therefore we can find the volume of the cell. I am having trouble understanding how to use this data to find spacing inside a sphere.
     
  2. jcsd
  3. Oct 23, 2010 #2
    anyone know where to start? I was thinking to use the density of the red blood cell but I am still having trouble figuring out how to eventually get to mean spacing
     
  4. Oct 24, 2010 #3

    Borek

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    Staff: Mentor

    I would treat it as a simple geometry. Calculate volume available to each hemoglobin molecules, assume it sits in the center of a cube, calculate cube edge length.

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  5. Oct 24, 2010 #4
    So if we take the molecule in the center, then would the separation be the distance between the center of two cubes? The separation is the cube length? I am having trouble understanding how you determine cube length. Are we supposing the molecule takes up all the possible room in the cube?
     
  6. Oct 24, 2010 #5

    Borek

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    Staff: Mentor

    It is the same.

    Oh come on, what is the formula for cube volume?

    Doesn't matter, even if it doesn't take whole volume. Space can be filled with anything - water for example.

    There is a possible problem if given molecule volume is higher than the cube volume, that would mean something is wrong.
     
  7. Oct 24, 2010 #6
    Thank you, my main problem was understanding what would happen if the molecule did not completely occupy the cube or so. Thanks for explaining it to me.
     
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